Today has been overcast for most of the day, but around 4 o'clock it started to clear a little, and I could witness Venus disappearing behind the Moon. It was a wonderful sight to see this amazingly bright little sphere of light vanish behind something that is almost invisible, the darker part of the crescent Moon. I used my 85mm Zeiss spotting scope, equipped with the zoom eyepiece for visual observation. I also shot some images right before Venus disappeared with the Coolpix 4500. Enjoy the views, and I hope it will still be clear when Venus reappears!

The Royal Mail (UK) celebrates 50 years of the BBC's Sky at Night television programme with the issue of 6 stamps that show 6 different Caldwell Objects. On the stamps you see 6 wonderful colour images of 4 planetary nebulae, a galaxy and an emission / reflection nebula.

The last few weeks the weather has been very good, and every night an hour before sunset, we took a long walk through the fields just down the road where we live. It's amazing what you sometimes can see when taking your time. Every evening we noticed not only different animals and plants, but also different celestial sights. Most of the time we carry a small digital camera with us, to record some of the things we encounter on our daily walk. Here are a few images we shot last week, two of a sunset and one of the Moon which is visible through the branches of a huge tree. Hope you enjoy the pics.

On Thursday April 19th their was a pretty pairing of Venus and the Moon in the evening sky. I shot a few images with the Nikon Coolpix 4500 mounted on a tripod. On the first image you see the crescent Moon hanging to Venus's lower right, right over our neighbours house. On the second image you can see the earthshine on the part of the moon that is not illuminated by the Sun. On the third image you can see a close up of Venus and the Moon. Click on the thumbnail images to enlarge!

Introduction
It has been quite a while since you heard from me but finally I managed to find some time to give you an update on the performance of my new telescope, the 300mm Dobson from Orion Optics UK. I have been using it on several nights during the last few months and in this article you find a summary of the results of these more or less short observing sessions.

Overall impressions
After the first 5 to 10 observing sessions in my light-polluted suburban backyard (limiting magnitude 4.5 to 5.3), there is one thing that is very clear to me: aperture really can make the difference. When I was observing with Jo, a fellow observer who also got the Orion Optics UK 300mm very recently, we both agreed that the views with the 300mm on a less than average night are better than with our 200mm telescopes on the best night ever. Not only the amount of detail you see in many deepsky objects is simply amazing, the bigger scopes also make it possible to observe a lot of objects that were more or less invisible in the 8-inch telescopes we've looked through. I have been told many times that buying a telescope with a larger aperture is of little or no use if you live in the suburbs. Well, maybe that is through for one class of objects, the fainter galaxies, but for all the other objects I have been looking at during the last few months (including the big bright galaxies) the story is very different. They all look better, brighter, more detailed and some of them even show some colour!

I also am convinced that for visual observing, this is the system for me. It is very quick to set up, and following objects by hand is very easy with this scope. If you have the balance right, you can follow objects without a problem, even with magnifications up to 457x (I've tested this with a 3.5mm Pentax XW eyepiece I borrowed from a fellow observer). Also switching eyepieces at higher magnifications isn't a big Issue, if your eyepieces have a large apparent field of view (68 to 82 degrees). With my Vixen LV eyepieces, which have an apparent FOV of 50 or even 42 degrees, the objects rush out of view at higher magnifications. All in all I can say that this will definitely be my most used telescope for deepsky observing.

Open clusters
I have observed a large number of open clusters, M35 and NGC 2158, M36, M37, M38, M48, M67, the double cluster, NGC 7789, NGC 2301, NGC 457, M103, and many more. They all looked brighter, showed more fainter stars and simply looked beautiful, a real pleasure to just look at and enjoy the views! I also tested the Dob by hopping along 20 not so bright clusters in Cassiopeia, which I had observed with the 8-inch in the last few years. I remember that with the 8-inch most of them where very difficult to detect from my magnitude 5 backyard, but with the 300mm dob they all were visible on first sight. Other fainter / smaller clusters like NGC 1907 (near M38) and NGC 2158 (near M35) where resolved into many pinpoint stars. All the very small or faint clusters, which my TAL 200K simply did not show, were no problem for this telescope. The eyepiece I liked most for the clusters where two I borrowed from fellow observers, the 22mm and the 24mm Panoptic from Televue. I probably will replace the 32mm Plossl by the 22mm Panoptic (about the same field of view, but much higher magnification and excellent exit-pupil of 4mm).

Planetary nebulae
I was in for a big surprise! I only looked at a few planetary nebulae but I will never forget my first look at the Blue Snowball (NGC 7662). This planetary is really blue! I never saw any colour in my 8-inch telescope when observing deepsky objects, but in the 300mm, bang! The colour was best with the 24mm Panoptic I borrowed, but in the 12mm Nagler and the 7mm Pentax the colour was also very easy to see. Last Sunday night I observed NGC 6210 in Hercules. This planetary was also strikingly blue in my 7mm Pentax and 12mm Nagler. I also tried the UHC and OIII filters. NGC 6210 became brighter, but the colour disappeared. I liked the view without the filters best. Then I visited another planetary last night, M 97 in Ursa Major. I was surprised that I could see it at all from my suburban backyard! I had never seen it before with the 8-inch, except one time when I was in Austria at 1800 meters I did see it with the TAL 200K. And what can I say, well with the UHC filter M 97 was very easy to see, a very big planetary, better than I ever seen it before, even better than at the star-party in Austria, which is at a higher altitude and has a much better seeing transparency. I tried to detect some details (the eyes of the owl), but I could not see them. However, I am convinced that I will see them from a dark sky-observing site. So what can I say about the planetary nebulae I've seen with this telescope? They all where brighter, much easier to see, and some of them even showed some colour.

Emission nebula
There's only one emission nebula I observed, and that was M42( and M43 of course). What a beauty at all magnifications, and what a detail! I looked at M42 at least on 5 different nights. In the Trapezium the E component was always visible, and the F component could be detected on 4 out of 5 nights. But the most stunning area was the bright central part of the Orion nebula. The details where amazing, even without a filter. Now I finally know what the Frons, the Occiput, the Pons Schroeteri and Sinus Gentilii are (I will publish a separate article on this!). There are lots of other structures left to detect, but on the first few nights I simply sat and took in the wonderful views. This has definitely become my favourite winter object. My 8-inch TAL cannot compete with the 300mm Dob on M42 / M43, I am really looking forward to the next winter, when I hope to see the Orion Nebula from a dark sky site.

Globular clusters
Last Sunday night I observed three globular clusters, M13, M3 and M92. I can be very short: they where all resolved right to the core. These objects are simply 10 times better than in the 8-inch. At 133x and 229x M13 looked liked a giant propeller, with chains of stars running from the core across the cluster into the dark sky, creating different streams of stars with dark lanes between them. I want to take up deepsky sketching again, but I think that I skip M13 ☺
The amount of stars is just overwhelming. M3 and M92 where also beautiful to see and I am looking forward to observe a few more globular clusters this year. They really look much better in the 300mm. The 200mm Tal only could resolve M13, M3 and M15 right into the core on the nights with a good seeing, but most of the time the larger parts of the globular clusters stayed hazy. Not with this telescope!

Galaxies
And now for the galaxies. I only had a look on a few of the bigger galaxies. They also looked a lot better than through the 8-inch. M81 and M82 in Ursa Major were the first two galaxies I had a look at. In my 8-inch M81 looked like a small circle and M82 like a small elongated patch of light. In the 300mm M81 looks really huge, a big more or less round (a little oval) galaxy. M82 looks like a big cigar. It shows a lot of detail at 133x and at 229x. The elongated bar of light is broken in two or three places by dark lanes and I could detect two "brighter" areas. M65 and M66 were very easy, even on a night with a mediocre seeing and transparency. Last Sunday night I had a look at M51 and it's companion NGC 5195. Now through my 8-inch I only saw two more or less points of light, with a little haze around it and sometimes, from my backyard, I could not see them at all. Last Saturday, when the transparency was not so good (a lot of high clouds) I did see a little more than usual, but it still was a bit disappointing. Sunday night however, the sky was a lot clearer and there it was, M51 looked like a really big round smudge of light with a very bright core and some areas of uneven brightness detectable in its disk like structure. NGC 5195 was a lot smaller but also had a very bright core. I am sure that from a dark-sky site, M51 will reveal some of its spiral structure.

Well, that’s all for now. I hope we will have a lot of clear skies in the next few months, and I will keep you updated! If you have any questions on the scope, or want to react on this article, please feel free to do so.

Well, after a turbulent five months I am glad to be back again. During this period my father became very ill, and a few weeks ago he sadly passed away in hospital after a 10-week stay on an intensive care unit. As you can imagine I had other things on my mind than maintaining my blog and site.

It is not easy to go through such dark times in your life, but luckily, there is always someone or something that helps you to forget everything for a little while, like being with your family and friends. And every now and again, I also found a little comfort being outside under the stars, alone or with Leo, a fellow observer. I didn’t log any of these short observing-sessions but simply tried to enjoy the views and forget all the troubles for a few minutes. Sitting under the stars one night, I thought about Frodo (Lord of the Rings) who gets a most wonderful gift from Lady Galadriel: the light of Earendil’s star caught in a small crystal bottle filled with water from her fountain. She presents this gift to Frodo saying:

“May it be a light to you in dark places, when all other lights go out”.

And that’s how I felt about the stars that night. They were lights that somehow guided me trough a dark period of my life.

Just after my father died, we went outside one evening, and in the western sky we saw a very bright Venus. My girlfriend said to me, think of this bright light as being your father, shining for us. This thought somehow was very comforting, so maybe that’s an idea for anybody who loses a dear one. Give him or her a place in the starry sky, so that when you’re under the starry sky, you have the feeling that he / she is with you. I still miss my father very much, but when I go out tonight and see Venus shining in the twilight, I will do this with positive feelings, thinking about the good times we had together. That’s what he would have wanted me to do.

Intro
I have been observing the deepsky visually for a few years with my 8-inch TAL 200K mounted on a Synta EQ6. What I didn’t like about this setup were two things: it was a lot of work to take it apart for transport when I wanted to go to a dark sky site and the aperture was just a little too small for deepsky observing from my light polluted backyard. A lot of objects just stayed out of reach.

So I wanted a telescope that could be setup and taken apart quickly and I wanted a telescope with a little more aperture. Set-up should only take a minute or two. I also wanted to be able to put it into my small family car without any help and carry it around on my own. My lower back problems limited the weight of each component to 20 Kilograms maximum. Because of these back problems, I also wanted a telescope that allowed sit-down observing. I decided to buy a closed tube Dobson with the largest aperture I could manage on my own.

After reading many reviews, test reports and discussing equipment with fellow observers, I decided to go for the 300mm f / 5.3 Dobson from Orion Optics UK. The OTA (with cradles) and the rocker box both weigh about 15 Kilograms (without the alterations and additions that were made). The tube is about 155 Centimeters long and is ideal for sit-down observing.

After 8 weeks the telescope arrived. It came in two boxes, one small box containing the rocker box, and a big box with the complete tube assembly. The Crayford focuser was slightly damaged, probably during transport. It was replace by Orion Optics UK immediately. (You can enlarge all images in this article. Just move the mouse-pointer over the image and click)

Rocker Box and tube assembly and tube-rings
The rocker-box is made of aluminum about 10mm thick. The setup (only Allen screws) took me about 3 minutes. It looks very stable and sturdy. The tube-cradles are attached to a pair of large rings that fit into the rocker box. The rings can be adjusted in all directions using setting screws. This way the rings can always be adjusted to fit the rocker-box. The rings rotate in the rocker-box on four pieces of Teflon. The base of the rocker-box rotates on three Teflon disks that are fitted to the three legs of the base.

The tube is made of aluminum and sprayed with bright white paint. On both ends there is an aluminum black ring, held in place by a few small screws. The finder scope is mounted with a dovetail and bracket. The bracket and the finder scope are in the same black and white color as the tube. The 2-inch Crayford focuser is black. The finishing of the whole tube-assembly looks very good. All in all, the entire telescope looks nice (aesthetically). The initial setup of the rocker-box and tube-assembly takes only 5 to 10 minutes. To give you an idea of the size and the looks of the telescope, here it is, a proud owner included

The mirrors / collimation
The secondary mirror is held in place with a 4-vane spider. You can center the secondary in the tube by tightening and/or loosening 4 large setting screws on the outside of the tube. On the back of the mirror cell you will find 4 screws. With the central screw you can move the secondary “up” and “down” through the tube. This way you can center the secondary in the focusser. When the central screw is loosened you can also rotate the secondary. Once you centered the secondary ( in the tube and in the focusser), you can fasten the central screw, and collimate the secondary, by using the other three screws. (For an image of the secondary and the 4-vane spider see image below under "flocking paper in the tube")

The primary mirror is held in place by a three-point mirror cell. Collimation of the primary is very easy, and must be done manually with the help of some collimation tool (laser, Cheshire, sight tube etc.). You simply loosen three Allen screws by hand. You then “collimate” the mirror using three large setting screws. This is also done manually. When the collimation is finished, you simply fasten the three Allen screws “finger tight”. These three screws hold the collimated primary in place.

As for the quality of the mirrors, I can only tell you about the primary. You get a detailed test-report with your mirror, telling you the different values like Strehl, PV wave front, RMS etc. as well as the serial number of the primary. I do not know a lot about optics, so I rely on others if it comes to explaining the graph and the data on the datasheet. According to Harry Rutten (author of Telescope-optics), whom I showed the test-report, the mirror is of an excellent quality. The Strehl ratio is 0.986, the PV wave front is 0.115 wave and the RMS is 0.019 wave. To see the test report, click on the image below.

Finder-scope
I have tried the finder-scope a few times. I always wear glasses (astigmatism) when observing, and I noticed that the eye-relief is far from sufficient for me. I only see a very small part of the field of view. If I take of my glasses, the eye relief is ok. The finder scope will be replaced with a Telrad or some other one-power finder in the near future, because I will use it only for aligning the telescope on two or three bright stars. The rest is up the Argo Navis Digital Telescope Computer.

Crayford focuser
The Crayford focuser works fine. Focusing is no problem, even at high magnifications. It runs very smooth, and the friction can be adjusted simply by turning a setting screw. With a second screw the focuser can be locked. The only downside is that I have to use an extension with all eyepieces I tried (2-inch and 1.25-inch).

Alterations/additions
In the last few weeks, together with Leo and Joop from the local astronomy club, we managed to make a few alterations and additions to the telescope and mount:

Together with these alterations and additions, the tube assembly weighs 18 Kg and the rocker-box 17 Kg.

1: the fan
I added a fan to the backside of the tube, which covers the complete aperture. The fan draws in the air from the top of the tube. The air goes through the tube and past the mirror, and exits behind the mirror, through the fan. This way a laminar flow is created within the tube, and turbulences due to difference in temperature inside the tube disappear within a few minutes. I tested the fan 4 or 5 times until now, and even when I moved the scope from a heated room into my backyard, just a few minutes after the fan was switched on, the turbulences inside the tube were gone. It works perfectly. Leo had tested this system on two other Newtonians, and it worked, so we expected it to work just fine on my new scope.

How did we construct this fan? Leo used a piece of very sturdy foam about 1 inch thick. We got a fan that is used for cooling PC’s with the option to have variable speed. We cut an opening in the centre of the foam in which the fan fits nicely. After that Leo connected an external pot-meter to the fan so that the speed can be varied from absolutely zero to fast. I finished the fan with flocking paper and 4 strips of Velcro to attach the fan to the backside of the tube.

2: digital setting circles DTC Argo Navis
On my EQ-6 I used Argo Navis digital setting circles for locating objects. Because the 300mm Orion Optics UK will be my deepsky telescope from now on, I decided to transfer the Argo Navis from the EQ6 to the Orion Optics. I ordered a set of new (10.000 steps) optical encoders and a few cables from Wildcard Innovations, the company that produces the Argo Navis. Joop Wiersma managed to attach the decoders and the Argo Navis to my new dob just wonderfully. He already had some experience because he build the Argo Navis onto his own Orion Optics 300mm and with my scope he even made a few improvements to the whole construction. He needed some small parts like bolts, nuts and a few pieces of aluminum (total price 10 Euros) and what he constructed in a few hours is amazing. It not only looks very good, it works 100%!

Below you will find some images. From left to right you see the Argo Navis, the altitude encoder and the azimuth encoder. If you like to know about the complete construction in detail, you just have to wait a little. It will be published in my blog, as a separate item. Anyway, the construction is made in a way that when I want to separate the tube from the rocker box, loosening one screw (manually, no screwdriver needed) and disconnect one encoder is enough. A very convenient and user-friendly solution. However, for transport I remove the bracket that secures the altitude encoder to the rocker-box completely to prevent it from getting damaged. A few yards of Velcro were used to keep all the cables in its place.

And here's a shot of the complete construction...................

3: power supply for computer and fan
Of course the Argo Navis and the fan both need some power. I chose to attach two sealed led-acid batteries to the floor of the rocker-box again with some Velcro. One is connected with the fan, the other with the Argo Navis. I used cigarette lighter plugs to connect the fan and Argo Navis to the batteries. This makes it very easy to unplug everything after an observing session. Because of the weight of the batteries, everything feels even more stable. The rocker-box is the best place for the batteries. You can turn the scope in whatever direction, all the cables stay in exactly the same place. A simple but perfect solution.

4: tube extension to keep out stray light
Another addition I made is a tube extension that both keeps out stray light and prevents the secondary from dewing. The tube was made from 1mm thick cardboard and yes, a few feet of Velcro again. I did not have a chance to test it because the extension is a bit heavy, and I need to attach a counterweight to the tube to keep it balanced. I simply will add another cradle to the tube to act as the counterweight. It can easily slide up and down the lower half of the tube, to adjust the balance.

5: flocking paper in the tube
I added some flocking paper to the inside of the tube, but only to the part of the tube that I see when I look through the focuser directly without using an eyepiece. I hope the flocking paper prevents reflection of incoming stray light directly into the eyepiece. I added the flocking also to the inside of the tube extension.

To be continued………..
So far for the hardware. My next article will be about “first light” and my experiences with the telescope under the stars. Will the additions and alterations work? I hope that the weather will help a little in the next few weeks, so that I can give you some detailed observing reports. Until then I wish you all clear skies!

I have received a few questions about the height of the Crayford focuser on my 300mm Orion Optics UK Dobson. Here are three images that show the Crayford in its different positions. On the first image you can see the height of the focuser when it's inside the tube, 6 centimeters. The second image shows the focuser when completely outside, 9 centimeters. So you only have 3 centimeters of travel. On the third image you see the focuser with an extension and completely outside. The total height is 14 centimeters. I have to use the extension on all my 1.25 eyepieces as well as on the Zeiss zoom-eyepiece. For my 32mm Televue plossl, the extension is just a few millimeters to short. I have to pull the eyepiece a little out to get it into focus.